appropriate bit of bunting was fluttering on the halliard at the top of
the signal mast.

"We are directed," Jack read on, "to be ready within thirty minutes. We
must follow the 'Oakland' down the bay at a cruising speed of sixteen
miles an hour. Once out of the bay, the 'Oakland' will signal our
formation to us."

"Do you see the boat the Rhinds signal is going up on?" laughed Hal
Hastings. "It is going up on the submarine 'Thor.' According to the old
Norsemen tales Thor was The Thunderer--also the fellow who struck with
the big hammer. It looks like a Rhinds boast that they are to do big
things on this lightning cruise."

"Yes; Thor was an old Norse god," muttered Captain Jack. "And the early
Norsemen were very largely pirates. Perhaps we are to take the signal
on the 'Thor' as an intimation that Rhinds is out to play pirate in
earnest on this cruise."

As Benson uttered these words he felt an odd little shiver run over him.
Yet he gave it no more thought. Little idea had he, at that moment, how
prophetic his words were likely to be!

In half an hour, as planned, the "Oakland," after firing a warning gun,
steamed away from her moorings. Gradually the gunboat's speed
increased, until the full sixteen miles were being made--miles, instead
of knots, since gasoline boats, like these submarines, are usually rated
by miles instead of by the longer "knot."

It was a rattling rate of speed to exact from these little craft, when